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Railways Quantitative Aptitude Power, Surds And Indices Sample Paper Surds Indices Sample Test Paper-4

  • question_answer
    \[\frac{{{2}^{n+2}}-2({{2}^{n}})}{{{2}^{(2n+2)}}}\] when simplified is

    A)  \[1-2({{2}^{n}})\]      

    B)  \[{{2}^{n+3}}-\frac{1}{4}\]

    C)  \[\frac{1}{{{2}^{n+1}}}\]     

    D)  \[\frac{1}{{{2}^{n-1}}}\]

    Correct Answer: C

    Solution :

    [c] \[\frac{{{2}^{(n+2)}}-2\left( {{2}^{n}} \right)}{{{2}^{(2n+2)}}}=\frac{{{2}^{n}}\cdot {{2}^{2}}-{{2.2}^{n}}}{{{2}^{2}}\cdot {{2}^{2n}}}=\frac{{{2.2}^{n}}\left( 2-1 \right)}{{{2}^{2}}{{.2}^{2n}}}\] \[=\frac{1}{{{2.2}^{n}}}=\frac{1}{{{2}^{(n+1)}}}\]


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